Sri Lanka is home to ancient irrigation systems which have been perfected through consistent improvements and construction over 1600 years. Small village cascades are linked up with massive reservoirs in intricate hydraulic systems. The small village tanks (weva) were managed by villagers while the large reservoirs were managed and operated by designated families. Collective decisions were taken in a way to accommodate to the high climate variability characteristic of the tropics. The tank irrigation system blended seamlessly to the natural environment, which has been maintained carefully through the preservation of a diverse array of plants and trees that occupy the surrounding land.

During the 20th century, due to poor knowledge of the function of the ancient tank systems, they were destroyed when modern large scale irrigation projects were constructed. These projects have yet failed to secure reliable water supplies. The restoration and use of the ancient tanks is nowadays more significant. Moreover proper maintenance of old tanks has also helped to reduce the malaria epidemic in the region, since abandoned tanks are breeding media for malaria vectors.